Disk files are information storage devices which utilize at least one rotatable disk with concentric data tracks containing the information, a head (or "transducer") for reading data from or writing data to the various tracks, and a head positioning actuator connected to the head for moving it to the desired track and maintaining it over the track centerline during read or write operations. The transducer is attached to an air-bearing slider which is supported adjacent the data surface of the disk by a cushion of air generated by the rotating disk. The slider is connected to a support arm of the head positioning actuator by means of a suspension.
The suspension provides dimensional stability between the slider and actuator arm, controlled flexibility in pitch and roll motion of the slider relative to its direction of motion on the rotating disk, and resistance to yaw motion. In conventional disk files the suspension provides a load or force against the slider which is compensated by the force of the air-bearing between the slider's air-bearing surface and the disk surface. Thus, the slider is maintained in extremely close proximity to, but out of contact with, the data surface of the disk. The suspension typically comprises a load beam, which is mounted at one end to the actuator arm, and a flexure element which is attached to the other end of the load beam and supports the slider. The load beam provides the resilient spring action which biases the slider toward the surface of the disk, while the flexure provides flexibility for the slider as the slider rides on the cushion of air between the air-bearing surface and the rotating disk. Such a suspension is described in assignee's U.S. Pat. No. 4,167,765. An example of a conventional slider for use with such a suspension is described in assignee's U.S. Pat. No. 3,823,416.
In the conventional slider-suspension assembly, the slider is mechanically attached to the flexure element of the suspension by epoxy bonding. The electrical connection between the transducer and the disk file read/write electronics is made by twisted wires which run the length of the suspension load beam and extend over the flexure and slider. The ends of the wires are soldered or ultrasonically bonded to the transducer leads on the slider. Another type of suspension is a composite or laminated structure comprising a base layer with patterned electrical leads formed thereon and an insulating cover layer, as described in IBM Technical Disclosure Bulletin, Vol. 22, No. 4 (September 1979), pp. 1602-1603 and Japanese Kokai Nos. 53-74414 (July 1, 1978) and 53-30310 (Mar. 22, 1978). In the laminated suspension described in Japanese Kokai No. 53-74414, the slider is epoxy bonded to the laminated suspension and the transducer leads are soldered to the electrical leads formed on the suspension. Assignee's U.S. Pat. No. 4,761,699 describes a laminated suspension for use with a conventional slider wherein solder ball connections provide both the mechanical connection of the slider to the laminated suspension and the electrical connection of the transducer to the leads on the laminated suspension.
Another type of slider is a "negative pressure" or "self-loading" slider, such as disclosed in assignee's U.S. Pat. No. 3,855,625. In contrast to suspensions used with conventional sliders, in suspensions for use with negative pressure sliders it is desirable to maintain the negative pressure slider adjacent to the data surface of the disk with as low a "loading" force as possible since the slider creates a vacuum between it and the disk which holds the slider adjacent to the data surface. Assignee's U.S. Pat. No. 4,286,297 describes a suspension for use with a negative pressure slider.
One of the problems with disk files using the conventional suspension or the laminated type suspension is that after the slider has been in stationary contact with the disk surface for just a short period of time, the slider tends to resist translational movement or stick to the disk surface. This "stiction" is caused by a variety of factors, including static friction and viscous shear forces and surface tension created by the disk lubricant. Even in those disk files which have disks with extremely smooth unlubricated disk surfaces, stiction may occur because of the strong intermolecular attraction at the interface between the smooth disk and slider surfaces. One technique for solving the stiction problem is to use some type of load/unload mechanism to assure that the slider never contacts the disk surface when the disk is not rotating. Assignee's U.S. Pat. No. 4,141,049 describes a mechanism for loading and unloading a negative pressure slider to and from the disk surface. A laminated type suspension for a negative pressure slider which also expands and contracts to load and unload the slider is described in assignee's U.S. Pat. No. 4,670,804.
An additional problem with conventional slider-suspension assemblies is the damage caused to the head or disk when the slider suddenly impacts the disk, such as may occur during shipping of the disk file.